poolman1126

I installed a pfc a little over a week ago and having some probs. Same as mentioned in other threads, I think. But I'm not positive on that so I thought I'd post my own and see if someone can tell me specifically whats causing mine, if they're the same as others had:

Not all, but most the time my idle jumps up and down. From about 800 up to 1200 or so and back, etc. When driving everything is fine. Turn a/c on and idle goes from 800 down to 300 or so and back, etc. Changing fan speed will correct it but only temporarily. When stopped or driving, a/c will suddenly get not-so-cold but changing fan speed will make it cold again, until it does the same later all over again (I wonder if this is low freon, but this is the first I've had to use a/c since buying the car so I dunno if it was a previous problem)

After reading the threads, it sounds like people with a/c probs, there's didn't work AT ALL. So I dunno if this is the same or not. I did NOT splice the a/c wires on the harness/pfc. Just plug and play, (correct pins were already clipped cuz I got it used.)

And I couldn't seem to find here exactly WHY people were splicing those wires. Is it to get a/c to work? Or to fix an idle prob? Both? Any help would be VERY appreciated! Thanks!

Oh, I went thru getting the pfc to learn idle with no load, park lights, and then a/c. It SEEMED to fix the prob, but only the sporadic idle part. And that was only temporary. When it started acting up again I reset the pfc, and that's when it started getting the sporadic idle with NO load.

cewrx7r1

iTrader: (2)

This has been discuss since so much that I am getting sick of hearing about it.

Please use the search on idle and A/C problems.

poolman1126

Did that for an hour. Didn't come up with answers to my questions. For example, are my symptoms the same as what others have experienced? From the threads I read it doesn't seem like it. Others didn't have a/c that w/o changing fan speed would go from cold-warm-cold-warm sporadically. And idle that would be fine on start up and then go sporadic-fine-sporadic-fine etc. These symptoms don't match what others had, I just wanted to know if they were pretty much the same anyway. I'm sorry if I didn't search long enough for your taste, but I got tired of reading all the "how-to"s to fix problems with the pfc, when I didn't even know if these were MY problems. Specifically when it's mentioned more than once that a 95 would not have some of the same issues.

cewrx7r1

iTrader: (2)

If you manually adjust your idle to work along with the PFC idle control, then you can get your idle to be normal with and without A/C.

When you make a manual change, it is also best to reset the ECU for it to learn gain.

poolman1126

Ok, I appreciate the tips/help. I tweeked with the idle a bit, but not much. I didn't know if that was such a good idea or bad to do after installing the pfc. My understanding was that the pfc would compensate on it's own. But I did try resetting the pfc. I'll go out to work on the both of them today. Thanks much!

cewrx7r1

iTrader: (2)

One thing most people do not know or understand is that most control systems (any type) have a limited range of control over what they do control when trying to stay within the designed target range. With the PFC it is fuel, air, rpm, and optionally timing.

When it has to go beyond the limit of any of these it starts oscillating. Thus you have to manually intervene to get it back in the ball park.

spyfish007

Ah intro to control systems theory .....

Adam

check your bac valve! i had the same problem, it puts more juice into the engine for the load ac takes

Str8Down

I am having this same problem with the stock ECU.

Spool Up

cewrx7r1 ....i saw your a/c fix, but it's useless without the BEM (Body Electrical Manual). I have the workshop manual, but w/o that BEM it's impossible to do your fix. I did a search looking to see if it's been scanned but no luck. My a/c was working fine on settings 1,4, and inbetween settings for about a month, and then it stopped working completely. I really need to get this fixed, any advice?

MichaelFregoe

iTrader: (1)

Look on the sensor moniter function of the PFC.. If the little circle next to A/C lights (turns Black) when you have the A/C on then the A/C works with the PFC . Check all 4 fan positions. Without the blackened circle the fan switch most likely has corroded contacts. The A/C will not work when that little circle is not black, Unless you splice the two wires and bypass the ECU for A/c control.
That does two things that are not good: 1) The ECU will not boost the idle for A/C operation (you'll get lumpy idle. 2) the A/C will not cut out at high throttle positions.


As far as idle problems adjust the idle air screw when the car is warmed up.

Spool Up

ok. i hooked up my datalogit and the check next to the the a/c on the monitor screen only comes on at settings 1 and 4 and some inbetween settings like i expected. Now, if it shows it to work on those two settings, then does that rule out the power fc as the source of my problem, or can the the box still be checked and the a/c still not work due to pfc related issues? I've tried searching and found a couple threads that always end up referring to cewrx7r1's fix, but since i'm missing some of the wiring diagrams and nobody seems to have them, i'm kind of **** out of luck. Can anybody paste some useful threads in here that I maybe overlooked?

my basic question though incase the above was confusing:
If the a/c checkbox is checked on the datalogit screen, does that mean my problem is definately non-pfc related, or could the pfc still be an issue?

MichaelFregoe

iTrader: (1)

Your problem is the fan switch or related grounding. Replace or clean the fan switch. Then ground the red wire coming off the back of the switch. Your troubles will be over

cewrx7r1

iTrader: (2)

The real problem IS THE PFC! The tolerances in voltage potential for proper A/C application is too narrow.

This problem has been around since 2001 and they have not fixed it. That is why the A/C still works if you plug back in the stock ecu.

Spool Up

Just to follow up, I found out what my problem was. Turned out that something was wrong with my relay. After plugging in the stock ecu and it still not working, I swapped in my friend's A/C relay and it worked. I put my old relay in after testing since he wanted his back, and it still worked. Maybe the relay just needed to be jiggled or something, but who knows. Anyways, my A/C still only works on fan settings 1,4, and some inbetween speeds, but much much better than nothing. Such fickle cars FD's are.

MichaelFregoe......I'm eager to try your suggestion of grounding the red wire off the back of the fan switch, but that will have to wait for another day when I get fed up with it being broken. That requires teaing everything off the dash, and I'm not quite up for that again. I actually already replaced the fan switch as well. The 94 textured panels I bought for my 93 came w/ the switch and other a/c controls. For now I think I won't push my luck and enjoy the fan settings I do have.

Spool Up

well, never mind. It stopped working again. bought a new relay from Mazda too and still not working. Oh well.

Spool Up

just following up again. Turned out that the previous owner had tampered with the 12v line to the compressor. I traced the wire back to an aftermarket connecter, and when i touched it, the wire pulled out of its connector. I just recut the wire and put a new connector on and everything is working well. My a/c only works on fan setting 1 right now, so i'm debating running a switch to the wire i just fixed to manually kick the compressor on whenever i want. It seems all the problems I have with my car are from the previous owners doing shitty work instead of problems related to high milage. Stupid stupid people.